1. Field of the Invention
The present invention relates to a pump casing made of sheet metal, and more particularly to a pump casing made of sheet metal and having a partition wall that divides the interior space of the pump casing into a suction chamber and a hydrocasing chamber.
2. Description of the Related Art
There have been known line pumps having a pump casing formed by pressing sheet steel such as stainless steel according to a deep drawing process.
One conventional line pump having a sheet-metal pump casing will be described below with reference to FIGS. 9 and 11 of the accompanying drawings. As shown in FIGS. 9 and 11, a line pump 71 has a sheet-metal pump casing 72 formed by pressing sheet steel such as stainless steel. As shown in FIG. 10, the pump casing 72 has a partition plate 73 that divides the interior space of the pump casing 72 into a suction chamber 74 and a hydrocasing chamber 75. In this specification, a hydrocasing chamber is defined as a chamber in which an impeller is disposed and a discharge pressure is developed. The line pump 71 also has an impeller 76 rotatably disposed in the hydrocasing chamber 75. The impeller 76 is fixedly supported on the free end of a shaft 77 of a motor M with a shaft seal 79 interposed between the shaft 77 and a casing cover 78.
The pump casing 72 has a suction port 80 communicating with the suction chamber 74 and a discharge port 81 communicating with the hydrocasing chamber 75. The pump casing 72 also has a suction flange 82 and a discharge flange 83 which are disposed around the suction port 80 and the discharge port 81, respectively.
As shown in FIGS. 9 and 10, the suction port 80 and the discharge port 81 have respective axes extending perpendicularly to the shaft 77, and are positioned diametrically opposite to each other across the shaft 77. The suction chamber 74 has a suction passage extending from the suction port 80 to an inlet region of the impeller 76. As shown in FIG. 10, the hydrocasing chamber 75 which houses the impeller 76 includes a discharge passage of a complex shape, such as a volute shape or the like, which extends from an outlet region of the impeller 76 to the discharge port 81. The suction chamber 74 also has a complex configuration because of a complex relative position between the suction port 80 and the inlet region of the impeller 80 as shown in FIGS. 9 and 10.
For fabricating the conventional line pump, it has been customary to separately produce the hydrocasing chamber 75 with the partition plate 73, and the substantially elliptical-shaped suction casing 72, and to weld the partition plate 73 and the suction casing 72 to each other. Alternatively, various components which form part of the suction chamber 74 and the discharge chamber 75 are welded to the partition plate 73.